Circuit component



March 26, 1957 C. E. ROEMER CIRCUIT COMPONENT Filed July 24, 1952 FIG. 1

FIG. 3

CARL

INVENTOR.

. ROEMEP United States PatentO CIRCUIT COMPONENT Carl E. Roemer, Lyndhurst, N. J., assiguor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application July 24, 1952, Serial No. 300,659 Claims. (Cl. 323-74) This invention relates to components for use in electrical circuits and more particularly to such components employed at high impedance points in electrical circuits.

One object of the present invention is to provide a shielded resistor for use at high impedance points in electrical circuits to minimize pick-up voltages.

Another object is to provide a combined resistor and condenser wherein the resistor is shielded to minimize pick-up voltages.

Another object is to provide a combined resistor and condenser wherein the capacitance of the condenser may be readily varied.

The shielded resistor alone or the combined resistor and condenser is especially adapted for use in the input grid circuit of a high gain voltage amplifier, Where the resistor is likely to pick up unwanted voltages. 'bined resistor and condenser comprises a conventional resistor of carbon or other material having an insulating coating thereon. A metallic coating may be applied over the insulating coating on the resistor in the form of a wound wire, a cylindrical sleeve, or in any other manner, and the metallic coating may be connected to one of the resistor leads. The outer surface of the metallic coating may be covered with a dielectric such as paper or mica, and an electrically conductiv. member may be positioned over the dielectric and be slidable on the dielectric and the other resistor lead relative to the resistor and associated metallic coating. The metallic coating forms one plate of the condenser and the member forms the other plate of the condenser and the coating and member cooperate to shield the resistor. The capacity of the condenser may be varied by sliding the member on the other resistor leadand when the condenser is adjusted to a suitable capacity, the member may be secured to the other lead and held in position thereby.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawing wherein three embodiments of the inventions are illustrated. It is to be expressly understood, however, that the drawing is for the purposes of illustration and description only, and is not to be construed as defining the limits of the invention. Accordingly, although the specification hereinafter states that the slidable member which constitutes the adjustable electrode of the condenser may be soldered to one resistor lead, it is understood that one aspect of the present invention contemplates the provision of a novel unit comprising a resistor cooperating with an adjustable condenser and that the solder is mentioned simply to suggest one of several possible means by which such resistor and adjustable condenser may be locked together when and if it is found desirable to lock the setting of the condenser after its adjustment for the particular circuit application intended.

In the drawing, Figure 1 is a longitudinal vertical section of a combined resistor and adjustable condenser constructed according to the invention, and

The com- 2,786,976 Patented Mar. 26, 1-957 Figures 2 and 3 are longitudinal vertical sections showing other forms of theinvention.

" Referring now to the drawing for a more detailed description of the novel circuit component of the present invention, the component is shown in Figure 1 as comare connected to the ends of the resistor and lead 5 is connected to one end of wire 3. Wire 3 provides a shield for the resistor to minimize pickup voltages when the re sistor is used at a high impedance point in an electric circuit.

Wire 3 may also form one plate of a condenser and, in this event, a dielectric 8, such as paper or mica, is placed over the wire. A cylindrical cup-shaped electrically conductive member 9 surrounds resistor 1 and associated wire 3 and has an aperture 11 in its end to receive lead 7. Member 9 forms the other plate of the condenser and is slidable on insulation 2 and lead 7 rela tive to wire 3 to vary the capacity of the condenser. When the capacity of the condenser has been suitably adjusted, the cup-shaped member may be secured to lead 7 by soldering, welding, or in any other suitable manner. A wire-like element 13 may be secured to member 9 to facilitate manually adjusting member 9 relative to wire 3, particularly when the circuit component is located in a relatively inaccessible place.

The combined shielded resistor and adjustable condenser is especially adapted for use in the input grid circuit of a high gain voltage amplifier, particularly where it is necessary to accurately phase the voltages applied to the grid by adjusting the condenser capacity.

In Figure 2, the shielded resistor and adjustable conthe resistor which may be secured to lead 5a. The outer surface of the cylinder 3a may be covered by a dielectric 8a, such as paper, mica or other suitable material, and cylindrical electrically conductive cup-shaped member 9a receives the resistor and associated shield and may be adjusted to any suitable position on lead 7a to vary the capacity of the condenser formed by metallic cylinder 3a and member 9a.

While wire 3 in Figure 1 and the member 3a in Figure 2 are shown as fixed to resistors l and la, .espectively, and extend the entire length of the resistors, and while members 9 and 9a are shown as extending approximately one-half the length of the associated resistors, it should be understood that the relative length of the members 3 and 3a and cylindrical members 9 and 9a is immaterial as long as they are telescoped one within another to overlap, so that the resistor is completely shielded by one or both of the members.

The arrangement shown in Figure 3 is substantially the same as the arrangements shown in Figures 1 and 2 except that a cylindrical electrically conductive cup-shaped member 3b extends substantially only one-half of the resistor length and a slidable electrically conductive member 9b, substantially the same length as resistor 1b, slides on member 3b and on lead 7!). Member 9b, after adjustment, may be soldered or otherwise secured to lead 7b substantially in the manner described in connection with Figures 1 and 2.

Although but three embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will be understood by those skilled in the art.

What is claimed is:

1. A circuit component of the class described comprising a resistor, and a pair of telescoping members of electrically conducting material insulated from and sur rounding said resistor to shield said resistor and forming the plates of a variable condenser, said members being slidable relative to one another to vary the capacity of the condenser formed by said members.

2. A circuit unit of the class described comprising a resistor having an elongated body, a lead at each end of said resistor body for connecting said resistor in an electric circuit, and a condenser comprising a pair of overlapping condenser electrode members insulated from and surrounding said resistor body and forming a shield for said resistor, one of said members being connected to one of said leads and the other member being slidable along the other lead relative to said first member to adjust the capacity of said condenser.

3. A circuit unit of the class described comprising a resistor, a pair of overlapping members of electrically conducting material insulated from and surrounding said resistor to shield said resistor and forming. the plates of a variable condenser, said members being slidable relative to one another to vary the capacity of the condenser formed by said members, and one of said members having an element secured thereto to facilitate adjustment of said member.

4. A circuit unit of the class described comprising a resistor, a shield of electrically conducting material insulated from the resistor and surrounding at least a portion of said resistor and forming one plate of a variable condenser, and a member of electrically conducting material receiving one end of said resistor and shield and cooperating with said shield to form the other plate of the condenser. said members being slidable relative to one another to vary the capacity of the condenser formed by said members.

5. A circuit unit comprising an elongated resistor, and a condenser insulated from the resistor and having as its electrodes a pair of relatively movable overlapping cup-shaped cylindrical electrode members which together substantially completely enclose said resistor to form a shield therefor which completely isolates said resistor from the intluence of external electrical fields.

6. A circuit unit comprising a resistor, and a pair of overlapping electrically conductive members insulated from the resistor and each surrounding at least a portion of said resistor to shield said resistor from stray electrical fields and forming the electrodes of a condenser, said members being movable relative to each other to adjust the capacitance of the condenser formed by said members.

7. A circuit unit comprising an elongated resistor, a pair of overlapping cup-shaped cylindrical electrode members insulated from the resistor and having a capacitance therebetween and together completely enclosing said resistor, the base of one of said members being disposed adjacent one end of said resistor and the base of said other member being disposed adjacent the other end of said resistor, one of said members being longitudinally slidable with respect to the other member to adjust the capacitance therebetween.

8. A unit according to claim 7 wherein there is provided a layer of solid dielectric material between the overlapping portions of said members, said one slidable member being slidable on said insulation layer.

9. A circuit unit comprising an elongated resistor, a lead at each end of said resistor for connecting said resistor in an electric circuit, a shield of electrically conducting material insulated from said resistor and receiving one end of said resistor and surrounding at least a portion thereof. and electrically connected to the lead at said one end, and an electrically conductive member receiving said shield and the other end of said resistor, said member being slidably adjustable along said other lead relative to said shield to form a variable condenser and adapted for rigid electrical connection to said other lead when adjustment of said member is completed.

10. A circuit unit of the class described comprising an elongated resistor, insulation means disposed on the outer surface of said resistor, a bare wire of electrically conductive material wound around the outer surface of the resistor on said insulation means so as to be insulated from said resistor and forming a shield for said resistor, and a cup-shaped electrically conductive member adapted to receive one end of said resistor and slidable relative to said wire to form a capacitance with said Wire which varies With the sliding of said member.

References Cited in the file of this patent UNITED STATES PATENTS 1,578,977 Frasse Mar. 30, 1926 2,111,710 Van Loon Mar. 22, 1938 2,368,476 Keister Jan. 30, 1945 2,464,376 Cohen et al. Mar. 15, 1949 2,518,225 Dorst Aug. 8, 1950 2,568,600 Wirk Sept. 18, 1951 

